won "Best Paper" at PacificVis 2014. Their paper presents a new approach to simplification of vector flow fields necessary to reveal essential features within a vector flow field. Traditional methods based on the topological skeleton successively remove pairs of critical points connected by separatrices, using distance or area-based relevance measures. These geometric metrics do not consider the flow magnitude, an important physical property of the flow. The new simplification scheme proposed is based on the recently introduced notion of topological robustness. Robustness enables the pruning of sets of critical points according to a quantitative measure of their stability, that is, the minimum amount of vector field perturbation required to remove them. This leads to a hierarchical simplification scheme that encodes flow magnitude in its perturbation metric.